Purification method of ultra-pure electronic-grade DMSO (dimethylsulfoxide)

Abstract

The invention relates to an ultra-pure electronic-grade DMSO purification method, and belongs to the field of wet electronic chemical purification. Comprising the following steps: S1, rectifying and purifying a prepared DMSO crude product, and separating moisture and light components in DMSO after the DMSO crude product passes through a light component removal tower to obtain DMSO and heavy components; s2, the DMSO obtained in the step S1 passes through a heavy component removal tower, heavy components and most of metal ions in the DMSO are removed, and DMSO stable in quality is obtained; s3, the DMSO obtained in the step S2 is purified with ion exchange resin, and residual metal ions in the DMSO are removed; s4, conveying the DMSO obtained in the S3 to a secondary light component removal tower to remove moisture in the DMSO, and S5, removing particulate matters and organic macromolecular impurities in the DMSO obtained in the S4 by using a membrane separation method, and then conveying the DMSO to a finished product tank for storage. The purification method is simple to operate and easy for industrial continuous production, and the obtained DMSO product is very high in purity and has a good application prospect.

Description

Technical Field

[0001] The invention belongs to the field of wet electronic chemicals, and in particular relates to a method for purifying electronic-grade DMSO. Background Art

[0002] Dimethyl sulfoxide (DMSO) is a non-protonic polar solvent that is soluble in both water and organic solvents. DMSO is used as a key raw material in developers and cleaning agents in integrated circuit manufacturing. The purity and impurity content of electronic-grade DMSO have a crucial impact on the yield, electrical properties and stability of integrated circuits. Generally, the metal ion content is required to be controlled within 1.0 ppb, and some semiconductor industries require the metal ion content of DMSO solvent to be controlled within 100ppt.

[0003] In the existing DMSO preparation process, the nitrogen dioxide method is widely used. The DMSO prepared by this method requires a post-treatment step of acid-base neutralization, which results in a high salt content in the finished DMSO product. After conventional distillation and purification, the purity of DMSO has been greatly improved to a certain extent, but it still does not meet the purity requirements of electronic-grade chemicals, such as metal impurities. The metal impurities in DMSO mainly come from the following aspects: 1. Some metal ions are introduced by catalysts, neutralizers, etc. during the production process; 2. The ability of distillation and purification to remove metals is limited; 3. The material transportation process is polluted by environmental elements. Some light metals such as sodium, potassium, aluminum, iron, calcium, and zinc are difficult to separate and remove by distillation, and these elements exist in large quantities in the surrounding environment, making purification very difficult, especially the preparation of ultra-high purity electronic-grade DMSO (99.99%).

[0004] In the existing DMSO purification technology, many purification processes will add a molecular sieve dehydration system after the ion exchange system. This is because the water content of the ion exchange resin is generally 40.0-60.0%. When the product flows through the resin tower, it will take out some water from the resin due to its strong water absorption, so it is necessary to add a dehydration step. Molecular sieve is a hydrated aluminosilicate with excellent adsorption properties. It can efficiently remove water from DMSO, but it will also increase the content of silicon, aluminum, and some rare metals in the product.

[0005] In order to solve the above problems, we proposed a DMSO purification method combining distillation purification and ion exchange resin purification. Summary of the invention

[0006] In view of the shortcomings of the existing technology, the present invention proposes an ultra-high purity electronic and DMSO purification method to prepare high-purity DMSO to meet the market demand for ultra-high purity electronic grade DMSO. First, a distillation system is used for purification to remove light components, heavy components and most metal ions in the crude DMSO product, and then an ion exchange resin is used to further purify and remove the residual metal ions in the DMSO. The DMSO purified by the resin is then passed through a secondary light removal tower to remove moisture.

[0007] A method for purifying ultra-high purity electrons and DMSO, comprising the following steps: S1. The prepared DMSO crude product is first neutralized with alkali solution and then distilled and purified. After passing through a light component removal tower, the water and light components in the DMSO are separated to obtain DMSO and heavy components; S2, passing the DMSO obtained in S1 through a deweighting tower to remove heavy components and most of the metal ions therein to obtain DMSO with stable quality; S3, purifying the DMSO obtained in step S2 with an ion exchange resin to remove the remaining metal ions in the DMSO; S4, transporting the DMSO obtained in S3 to a secondary light removal tower to remove water from the DMSO.

[0008] S5. Use membrane separation to remove particulate matter and organic macromolecular impurities from the DMSO obtained in S4, and then transport it to a finished product tank for storage.

[0009] In the preferred step S1, the light component removal treatment includes: the light component is condensed in a light component removal tower (the temperature in the light component removal tower is 80-130°C) by a condenser and then enters a reflux tank, and then refluxes to the upper part of the light component removal tower by a reflux booster pump in the light component removal tower to be separated as a light component product.

[0010] In the preferred step S2, the de-weighting treatment includes: heating the material (150-200°C) into a gas phase through a reboiler in a de-weighting tower, and the gas phase material rises to a condenser and condenses into liquid DMSO and then enters a storage tank, and a part of it is extracted and enters a resin tower for the next step of purification.

[0011] The water content of DMSO after purification in the distillation tower is 20-150ppm, and the total amount of metal ions is 100-1000ppb, wherein the metal ions include at least Na, Mg, Al, K, Ca, Cr, Mn, Fe, Co, Ni, Cu, Zn, and Pt.

[0012] In the preferred step S3, the purification of DMSO using ion exchange resin comprises two-stage resin tower purification: The first-level resin tower is filled with macroporous strong acid cation exchange resin, which is one of the following resins: Zhengguang CD552, Zhengguang C180H, Purolite C150H, Purolite CT-275, DuPont 252H, and Organo 200CTH; the second-level resin tower is filled with gel-type mixed bed resin, which is one of the following resins: Zhengguang ZGER8420, Zhengguang 8420, DuPont MB20, DuPont IN160, Lanxiao LX-M89, Lanxiao 6150U, and Dow HPR4800CL.

[0013] In the preferred step S3, the ion exchange resin needs to be pretreated before filling, and the ion exchange resin is rinsed with ultrapure water until the conductivity of the ultrapure water washed with the resin is 0.25-0.80㎲ / cm, and the excess water in the resin is discharged, and then the resin is immersed in DMSO and allowed to stand for 1-10 hours. After the wet resin and DMSO are mixed and the heat is released, the resin and DMSO mixture is filled into the resin tower.

[0014] Preferably, in step S3, the DMSO is purified using an ion exchange resin, and the DMSO flows at a rate of 5-50 BV / h in the primary resin tower and at a rate of 20-80 BV / h in the secondary resin tower.

[0015] In the preferred step S3, the water content of DMSO after resin purification is 200-1500 ppm, and the total weight of metal ions is 50-500 ppt.

[0016] In the preferred step S4, the inner wall of the secondary light removal tower is specially treated, and the treatment method is one of galvanizing, titanium plating, tantalum plating, lining PP, and lining PTFE, and the pipeline valve used for conveying materials is one or two of fluorine-lined materials, PTFE materials, and PFA materials. The bottom temperature of the secondary light removal tower is controlled at 70-100°C. The DMSO water content after treatment in the light removal tower is 20-150ppm, and the total weight of metal ions is 50-500ppt.

[0017] In the preferred step S5, the DMSO is separated by membrane to remove particulate matter and organic macromolecular impurities therein, the filter membrane used has a filtration accuracy of 0.05-0.5㎛, and the filter membrane material is one of HDPE, PVDF, PP, and PTFE.

[0018] The purification method provided by the present invention purifies DMSO by combining a distillation system with ion exchange, and the obtained product has high purity, DMSO content ≥ 99.99%, very low metal impurity content, and is of the quality of G5 electronic grade reagent. The quality of the common electronic grade DMSO on the market is G3 electronic grade, and the price of G4 electronic grade DMSO is very high, and the market supply is small. The purification method is simple to operate, the product purity is very high, it is easy to industrialize and continuously produce, and has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The present invention provides a schematic flow chart of a method for purifying ultra-high purity electronic-grade DMSO. DETAILED DESCRIPTION

[0020] Example 1 A method for purifying ultra-high purity electrons and DMSO, according to Figure 1 The DMSO purification process schematic diagram shown in the figure specifically comprises the following steps: The crude DMSO product was neutralized with NaOH solution to a pH of 8.0 (metal ion content is shown in Table 1) and then passed into a light component removal tower (tower bottom temperature 85°C). The light component was condensed in the condenser in the light component removal tower and then entered the reflux tank. The reflux booster pump in the light component removal tower then refluxed to the upper part of the light component removal tower. Water and light components were separated from the top of the tower. The obtained DMSO and heavy components are passed into a de-weighting tower, and the DMSO is heated to 190°C by a reboiler to become a gas phase and rise to a condenser, thereby separating DMSO from the heavy components. DMSO is extracted from the top of the tower. The water content and metal ion content of the DMSO after distillation and purification are shown in Table 1; The extracted DMSO was transported to the primary resin tower; the resin filled in the primary resin tower was Purolite C150H, which was rinsed with ultrapure water until the conductivity was 0.80㎲ / cm, and the flowing water in the resin was drained, and then the extracted DMSO was immersed in the resin in the primary resin tower. After waiting for 10 hours, the ion exchange resin and DMSO ended the heat release and the DMSO in the resin was discharged, and the new DMSO solvent was passed through the resin tower at a rate of 30BV / h. The water content and metal ion content of the DMSO purified by the primary resin tower are shown in Table 1; The DMSO purified by the primary resin was transported to the secondary resin tower, and the secondary resin tower was filled with Lanxiao 6150U, and rinsed with ultrapure water until the conductivity was 0.25㎲ / cm, and the flowing water in the resin was drained, and then the DMSO purified by the primary resin tower was immersed in the resin in the secondary resin tower. After waiting for 2 hours, the ion exchange resin and DMSO ended the heat release and discharged the DMSO in the resin. The DMSO purified by the primary resin flowed through the ion exchange resin at a rate of 35BV / h in the secondary resin tower. The water content and metal ion content of the DMSO purified by the secondary resin tower are shown in Table 1; The DMSO purified by the two-stage resin tower is transported to the secondary light removal tower. The inner wall of the light removal tower is tantalum-plated. The pipes used to transport materials are all fluorine-lined materials, and the valves used are all PTFE materials. Water is separated from the top of the secondary light removal tower (the bottom temperature of the light removal tower is 90°C). The dehydrated DMSO is taken out from the bottom of the tower and filtered through a PTFE microfiltration membrane with an accuracy of 0.1㎛ to remove particulate matter and organic macromolecular impurities, and finally transported to the finished product tank for storage. The moisture and metal impurity contents of the DMSO finished product are shown in Table 1.

[0021] Table 1 Metal content and water content of DMSO at different purification stages Example 1-1 A method for purifying ultra-high purity electrons and DMSO, according to Figure 1 The DMSO purification process schematic diagram shown in the figure specifically comprises the following steps: The crude DMSO product was neutralized with NaOH solution to a pH of 8.0 (metal ion content is shown in Table 1) and then passed into a light component removal tower (tower bottom temperature 85°C). The light component was condensed in the condenser in the light component removal tower and then entered the reflux tank. The reflux booster pump in the light component removal tower then refluxed to the upper part of the light component removal tower. Water and light components were separated from the top of the tower. The obtained DMSO and heavy components are passed into a de-weighting tower, and the DMSO is heated to 190°C by a reboiler to become a gas phase and rise to a condenser, thereby separating DMSO from the heavy components. DMSO is extracted from the top of the tower. The water content and metal ion content of the DMSO after distillation and purification are shown in Table 1; The extracted DMSO was transported to the primary resin tower; the resin filled in the primary resin tower was Purolite C150H, which was rinsed with ultrapure water until the conductivity was 0.80㎲ / cm, and the flowing water in the resin was drained, and then the extracted DMSO was immersed in the resin in the primary resin tower. After waiting for 10 hours, the ion exchange resin and DMSO ended the heat release and the DMSO in the resin was discharged, and the new DMSO solvent was passed through the resin tower at a rate of 30BV / h. The water content and metal ion content of the DMSO purified by the primary resin tower are shown in Table 1; The DMSO purified by the primary resin was transported to the secondary resin tower, and the secondary resin tower was filled with Lanxiao 6150U, and rinsed with ultrapure water until the conductivity was 0.25㎲ / cm, and the flowing water in the resin was drained, and then the DMSO purified by the primary resin tower was immersed in the resin in the secondary resin tower. After waiting for 2 hours, the ion exchange resin and DMSO ended the heat release and discharged the DMSO in the resin. The DMSO purified by the primary resin flowed through the ion exchange resin at a rate of 35BV / h in the secondary resin tower. The water content and metal ion content of the DMSO purified by the secondary resin tower are shown in Table 1; The DMSO purified by the two-stage resin tower is transported to the secondary light-removal tower. The inner wall of the light-removal tower has not been specially treated. The pipes used to transport materials are all fluorine-lined materials, and the valves used are all PTFE materials. Water is separated from the top of the secondary light-removal tower (the bottom temperature of the light-removal tower is 90°C). The dehydrated DMSO is taken out from the bottom of the tower and filtered through a PTFE microfiltration membrane with an accuracy of 0.1㎛ to remove particulate matter and organic macromolecular impurities, and finally transported to the finished product tank for storage. The moisture and metal impurity contents of the DMSO finished product are shown in Table 1.

[0022] Table 1 Metal content and water content of DMSO in different purification stages of Example 1 and Example 1-1

[0023] As shown in Table 1, the metal impurity content of DMSO after purification by two-stage resin tower is controlled within 20ppt, and the water content is above 1000ppm. After DMSO is treated by ordinary light removal tower, the water content is reduced to 72ppm, but the metal impurities rise to ppb level. The metal impurities of DMSO treated by tantalum-plated two-stage light removal tower are almost unchanged, and the water content is reduced to 85ppm.

[0024] Example 2 A method for purifying ultra-high purity electrons and DMSO, according to Figure 1 The DMSO purification process schematic diagram shown in the figure specifically comprises the following steps: The crude DMSO product was neutralized with NaOH solution to a pH of 7.5 (metal ion content see Table 2) and then passed into a light removal tower (tower bottom temperature 115°C). The light components were condensed in the condenser in the light removal tower and then entered the reflux tank. The reflux booster pump in the light removal tower then refluxed to the upper part of the light removal tower. Water and light components were separated from the top of the tower. The obtained DMSO and heavy components are passed into a de-weighting tower, and the DMSO is heated to 210°C by a reboiler to become a gas phase and rise to a condenser, thereby separating DMSO from the heavy components. DMSO is extracted from the top of the tower. The water content and metal ion content of the DMSO after distillation and purification are shown in Table 2; The extracted DMSO was transported to the primary resin tower. The resin filled in the primary resin tower was Organo 200CTH. It was rinsed with ultrapure water until the conductivity was 0.45㎲ / cm. The flowing water in the resin was drained, and then the extracted DMSO was immersed in the resin in the primary resin tower. After waiting for 7 hours, the ion exchange resin and DMSO ended the heat release and the DMSO in the resin was discharged. The newly extracted DMSO solvent was passed through the resin tower at a rate of 50BV / h. The water content and metal ion content of the DMSO purified by the primary resin tower are shown in Table 2. The DMSO purified by the primary resin was transported to the secondary resin tower, and the secondary resin tower was filled with Zhengguang mixed bed resin 8420, and washed with ultrapure water until the conductivity was 0.28㎲ / cm, and the flowing water in the resin was drained, and then the DMSO purified by the primary resin tower was immersed in the resin in the secondary resin tower, and after waiting for 1 hour, the ion exchange resin and DMSO exothermic ended and the DMSO in the resin was discharged, and the DMSO purified by the primary resin flowed through the ion exchange resin at a rate of 55BV / h in the secondary resin tower. The water content and metal ion content of the DMSO purified by the secondary resin tower are shown in Table 2; The DMSO purified by resin is transported to the de-lightness tower to remove moisture, and the DMSO purified by the two-stage resin tower is transported to the secondary de-lightness tower. The inner wall of the de-lightness tower is titanium-plated, the pipeline used for transporting materials is PFA pipe, and the valves used are all made of PFA material; the moisture is separated from the top of the secondary de-lightness tower (the bottom temperature of the de-lightness tower is 80°C), and the dehydrated DMSO is taken out from the bottom of the tower and filtered with a PTFE microfiltration membrane with an accuracy of 0.22㎛ to remove particulate matter and organic macromolecular impurities, and finally transported to the finished product tank for storage. The moisture and metal impurity contents of the DMSO finished product are shown in Table 2.

[0025] Table 2 Metal content and water content of DMSO at different purification stages in Example 2

[0026] Example 2-1 A method for purifying ultra-high purity electrons and DMSO, according to Figure 1 The DMSO purification process schematic diagram shown in the figure specifically comprises the following steps: The crude DMSO product was neutralized with NaOH solution to a pH of 7.5 (metal ion content see Table 3) and then passed into a light component removal tower (tower bottom temperature 115°C). The light component was condensed in the condenser in the light component removal tower and then entered the reflux tank. The reflux booster pump in the light component removal tower then refluxed to the upper part of the light component removal tower. Water and light components were separated from the top of the tower. The obtained DMSO and heavy components are passed into a de-weighting tower, and the DMSO is heated to 210°C by a reboiler to become a gas phase and rise to a condenser, thereby separating DMSO from the heavy components. DMSO is extracted from the top of the tower. The water content and metal ion content of the DMSO after distillation and purification are shown in Table 3; The extracted DMSO was transported to the primary resin tower. The resin filled in the primary resin tower was a conventional cationic resin ZGC107. It was rinsed with ultrapure water until the conductivity was 0.45㎲ / cm. The flowing water in the resin was drained. Then the extracted DMSO was immersed in the resin in the primary resin tower. After waiting for 7 hours, the ion exchange resin and DMSO exothermicity ended and the DMSO in the resin was discharged. The newly extracted DMSO solvent was passed through the resin tower at a rate of 50BV / h. The water content and metal ion content of the DMSO purified by the primary resin tower are shown in Table 3. The DMSO purified by the primary resin was transported to the secondary resin tower, and the secondary resin tower was filled with Zhengguang mixed bed resin 8420, and washed with ultrapure water until the conductivity was 0.28㎲ / cm, and the flowing water in the resin was drained, and then the DMSO purified by the primary resin tower was immersed in the resin in the secondary resin tower, and after waiting for 1 hour, the ion exchange resin and DMSO exothermic ended and the DMSO in the resin was discharged, and the DMSO purified by the primary resin flowed through the ion exchange resin at a rate of 55BV / h in the secondary resin tower. The water content and metal ion content of the DMSO purified by the secondary resin tower are shown in Table 3; The DMSO purified by resin is transported to the de-lightness tower to remove moisture, and the DMSO purified by the two-stage resin tower is transported to the secondary de-lightness tower. The inner wall of the de-lightness tower is titanium-plated, the pipeline used for transporting materials is PFA pipe, and the valves used are all made of PFA material; the moisture is separated from the top of the secondary de-lightness tower (the bottom temperature of the de-lightness tower is 80°C), and the dehydrated DMSO is taken out from the bottom of the tower and filtered with a PTFE microfiltration membrane with a precision of 0.22㎛ to remove particulate matter and organic macromolecular impurities, and finally transported to the finished product tank for storage. The moisture and metal impurity contents of the DMSO finished product are shown in Table 3.

[0027] Table 3 Metal content and water content of DMSO at different purification stages in Example 2-1

[0028] By comparing Table 2 and Table 3, we can see that under the same operating conditions, after replacing the cationic resin Organo 200CTH in the primary resin tower with Zhengguang ZGC107, the quality of the final product is also quite different due to the large difference in the adsorption capacity of the two resins for metal ions in DMSO.

[0029] The above-mentioned embodiments are only preferred technical solutions of the present invention and should not be regarded as limitations of the present invention. The embodiments and features in the embodiments of the present application can be arbitrarily combined with each other without conflict. The protection scope of the present invention shall be the technical solutions recorded in the claims, including the equivalent replacement solutions of the technical features in the technical solutions recorded in the claims. That is, equivalent replacement improvements within this scope are also within the protection scope of the present invention.

Claims

1. A method for purifying ultra-high purity electronic grade DMSO, characterized in that: The following steps are involved: S1, passing the prepared DMSO crude product into a light component removal tower for distillation and purification, the water and light components in the DMSO are separated, and DMSO with light components removed is obtained; S2, passing the DMSO obtained in S1 through a deweighting tower to remove heavy components and most of the metal ions therein to obtain DMSO with stable quality; S3, purifying the DMSO obtained in step S2 with an ion exchange resin to remove the remaining metal ions in the DMSO; S4, transporting the DMSO obtained in S3 to a secondary light removal tower to remove water from the DMSO; S5. Use membrane separation to remove particulate matter and organic macromolecular impurities from the DMSO obtained in S4, and then transport it to a finished product tank for storage.

2. A method for purifying ultra-high purity electronic grade DMSO according to claim 1, characterized in that, In step S1, NaOH solution is introduced into the crude DMSO product for neutralization (pH is adjusted to 7.5-9.5), and then the neutralized DMSO solution is introduced into a light-removal tower, and water and light components are separated from the top of the tower.

3. A method for purifying ultra-high purity electronic grade DMSO according to claim 1, characterized in that, In step S2, the DMSO after light removal is heated in a reboiler to become a gas phase and rise to a condenser, thereby separating DMSO from heavy components.

4. A method for purifying ultra-high purity electronic grade DMSO according to claim 1, characterized in that, The DMSO purified by distillation in step S3 enters two-stage resin towers for purification.

5. A method for purifying ultra-high purity electronic grade DMSO according to claim 5, characterized in that, The ion exchange resin filled in the primary resin tower is a macroporous strong acid cation exchange resin, which is selected from any one of Zhengguang CD552, Zhengguang C180H, Purolite C150H, Purolite CT-275, Dupont 252H, and Organo 200CTH.

6. A method for purifying ultra-high purity electronic grade DMSO according to claim 5, characterized in that, The ion exchange resin filled in the secondary resin tower is a gel-type mixed bed resin, which is selected from any one of Zhengguang ZGER8420, Zhengguang 8420, DuPont MB20, DuPont IN160, Lanxiao LX-M89, Lanxiao 6150U, and Dow HPR4800CL.

7. A method for purifying ultra-high purity electronic grade DMSO according to claim 5 or 6, characterized in that, Before filling the two-stage resin tower, the resin needs to be pretreated. The ion exchange resin is rinsed with ultrapure water until the conductivity of the ultrapure water washed with the resin is 0.25-0.80㎲ / cm, and the excess water in the resin is drained. Then the resin is immersed in DMSO and allowed to stand for 1-10 hours. After the wet resin and DMSO are mixed and the heat is released, the resin and DMSO mixture is filled into the resin tower.

8. A method for purifying ultra-high purity electronic grade DMSO according to claim 7, characterized in that, After the resin is filled, the DMSO purified by distillation is passed through the primary resin tower at a flow rate of 5-50 BV / h, and then passed through the secondary resin tower at a flow rate of 20-80 BV / h.

9. A method for purifying ultra-high purity electronic grade DMSO according to claim 1, characterized in that, The inner wall of the secondary light removal tower used in step S4 is specially treated by one of galvanizing, titanium plating, tantalum plating, PP lining, and PTFE lining, and the pipeline valves used for conveying materials are one or two of fluorine-lined materials, PTFE materials, and PFA materials.

10. A method for purifying ultra-high purity electronic grade DMSO according to claim 1, characterized in that: In step S5, DMSO is separated by membrane to remove particulate matter and organic macromolecular impurities, and the filter membrane material used is one of HDPE, PVDF, PP, and PTFE, and the filtration accuracy of the filter membrane is 0.05-0.5 μm.

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